Cleaning metal surfaces.



G. H. THOMPSON. CLEANING METAL SURFAGES. APPLICATION FILED MAY 20, 1913.

' rammedmay 2.6, 1914.

W/T/Vf5sf3 //VVE/V7 0/? aha/Z65 HerZerYT/zqmpwa UNITED STATES ra ENOFFICE.

CHARLES HERBERT THOMPSON, OF STOURBRIDGE, ENGLAND.

CLEANING METAL SURFACES.

To all whom it may concern:

Be it known that I, CI-IAnLns HERBERT THOMPSON, subject of the King ofGreat Britain, residing at Harrington ll'ouse, Amblecote, Stein-bridge,England, Fellow of the (lhemical Society, analytical and consultingchemist, have invented certain new and useful Improvements Relating tothe Cleaning of Metal Surfaces, of which the following is aspecification.

-During the manufacture of many forms of metal articles it is necessaryto subject the surfaces to a cleaning operation. Some articles, such asbaths and other hollowware, sheets and tubes of iron, steel and cop per,require to be cleaned before they can be properly enameled, galvanizedor plated. And other articles require to be cleaned after heating orannealing before a shaping or like operation can be performed thereon.

This invention relates to the cleaning of such metal surfaces in anelectrolyte.

Various processes have been proposed for cleaning metal surfaces byelectrolysis under the action of dircctcurrents, periodicallyreverseddirect currents and alternating currents, but none have been hithertoentirely successful owing either to the cost of maintaining the bath orof handling the articles placed therein.

According to this invention the objections to the known methods ofprocedure are avoided, and cleaning operations on the surfaces of metalarticles can be performed both effectively and economically.

The invention comprises the employment of a bath' of any suitablechlorid, sulfate or nitrate solution, passing an alternating currentthrough such bath, separating the electrodes from the articles to betreated by perforated or porous partitions, and placing the articles inthe bath without any metallic connection with the electrodes.

'l he accompanying sectional drawing illustrates diagrammatically oneconvenient means for carrying this invention into effect.

For the electrolyte I prefer a saturated solution of 'any suitablechlorid, sulfate or nitrate in water. Solutions of sodium chlorid ormagnesium sulfate are found to be among the most convenient, althoughsolutions of other chlorid, sulfate or nitrate salts may be employed.Also, solutions of suitable complex sulfates and chlorids containing.ammonia will give satisfactory re- Specificati on of Letters Patent.

Application filed May 20,1913.

sults. For example, a solution of an alum Patented May '26, 1914.

Serial No. 768,747.

containing aluminium and ammonium sulfate is satisfactory.

As regards the alternating current, any of the usual periodicitiesadopted in electrical power and lighting systems may advantageously beemployed, but I prefer a pcriodicity of 50 cycles per second. Thedensity of the current required may vary considerably according to theclass of work to be treated, and is best determined by actual trial onsample articles. The electrodes mayconsist of iron, carbon or other barsor plates connected to the current supply. These electrodes arecontained in perforated earthenware or other tubes or receptacles placedin the bath so that they are kept cntirelv apart from that portion ofthe bath which receives the articles to be treated. 01', the electrodesmay be separated from the main portion of the bath by perforateddivision plates placed across the bath. The ()bJtEUl'. ol' thepartitions is to prevent possibility of contact of the articles with theelectrodes. The perforations in the partitions enable free circulationof the electrolyte thcrethrough to be obtained. In all cases thepartitions employed for separating the electrodes from the main portionof the bath are of non-conductive material.

The articles to be treated are simply placed in the bath in such amanner that they are not connected metalically with the electrodes. Inthe case of sheets or tubes these may conveniently be mounted on awooden cradle which can be lowered into the bath. In fact, it is aconvenience to mount all other articles in this way for the reason thatnot only is the moving of the articles into and out of the bathfacilitated but it is also rendered possible to keep the articles in astate of motion within the bath, for example, by swinging the cradle orimparting to it a regular up and down movement.

In the diagram (1 indicates the bath of salt solution contained in atank 6, c are the electrodes, and d the perforated partitions whichseparate the electrodes from the main portion of the bath into which thearticles as e are placed. The cradle is indicated by dotted lines f.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:-

An electrolytic process for cleaning the surfaces of metal articlesconsisting in placing the articles without metallic connection articlesin suon, substantially as de- 10 w th the electrodes in a bath of anysuitable scribed.

chlorid, sulfate or nitrate solution, preve'nt- In testimony whereof Ihave signed my ing the articles from contacting with the name to thisspecification in the presence of electrodes, arranging said articles inseries two subscribing witn m:

with each other andthe electrodes, and passcmng 1113,3331 enson, ing analternating current through such Wi I w:

bath, the current by the said arrangement of J om: Mom,

articles and electrodes passing through the FRANCIS Manna.

